1. Field of the Invention
The invention relates to a method for automatically restarting of a temporarily shut-down internal combustion engine in a motor vehicle having a manual gear shift on the basis of conditions including the current actuation states of clutch and brake, and to a corresponding stop-start control device, according to the preambles of the independent claims.
2. Description of the Prior Art
In “micro-hybrid” motor vehicles, i.e. hybrid electric motor vehicles with stop-start functionality, the internal combustion engine may optionally be stopped automatically, i.e. shut down, if no motive power is needed, e.g. when waiting at traffic lights, and automatically restarted, i.e. started up when the driver needs motive power again. Such a stop-start operation results in a reduction in fuel consumption and noise emissions. Systems which allow such a stop-start operation are for example belt-driven integrated starter generators (B-ISG) or improved starter motors, with which the engine may continually be automatically restarted.
A method and a stop-start control device is known from DE 10 2004 024 213 A1. In this case, the stopped internal combustion engine is started again when the driver actuates the clutch and at the same time does not operate the service brake (hereinafter brake for short). However, this is not very convenient and ergonomic for the driver, since situations arise in which it would be desirable for him/her to be able to set off without having to keep the brake released while actuating the clutch.
FIG. 1 illustrates in a block diagram a more convenient and ergonomic method of performing a stop-start function in a motor vehicle with a manual gear shift. The left-hand side of FIG. 1 shows that the internal combustion engine is shut down when the vehicle is stationary or falls below a preset speed threshold, the gearbox is in neutral and the driver has released the clutch pedal. Additional stop conditions are possible. The right-hand side of FIG. 1 shows that the internal combustion engine is restarted when the driver depresses the clutch pedal while in neutral. The driver may then engage a gear and accelerate the vehicle.
However, the driver often depresses the clutch pedal much earlier than is necessary. For example, if the vehicle is in a line of vehicles at traffic lights, the driver depresses the clutch pedal and engages first gear when the light turns green, and not when the vehicles in front of him/her have started to move and it is his/her turn to set off. Such typical driver behavior is modeled in the European Drive Cycle: the test driver must engage gear five seconds before he/she sets the vehicle in motion. This typical behavior increases fuel consumption.